Low idle/dies after startup

[Toymanf]

Hello all
I have a 93 4runner with a 91 ls400 installed. It has the auto trans. The problem I am having is I have little to no fast idle during cold start. Also, on a warm restart, the engine fires and dies. During either scenario, if I hold the throttle open slightly, it starts and runs fine. When the a/c is turned on, you can hear/see the idle raise slightly. I have no codes in the ecu. I have confirmed the IDL switch is indeed closing and the ecu is seeing this signal. I have diassembled and cleaned the ISC valve and confirmed it is capable of opening and closing. I reinstalled the ISC valve in the fully open position, and the warm restart was perfect. The engine fired, ran at a slight fast idle, then came down to proper idle speed.
Any and all suggestions would be appreciated.
Thanks
Frank

 

[sleeperz]

check live data stream readings iff poss. coolant temp sensor reading important.check for carbon ring on throttle plate. ive seen people drill small hole in butterfly(ford and some others) as not to lose tps signal from turning idle screw/check for air bleed screw. check stuck egr valve.or air leaks before afm

 

[Toymanf]

Thanks for the reply.

I do not have the tools to check the data stream. I will look carefully at the things you have suggested and report back.
Frank

 

[Toymanf]

Does anybody have an ISC(idle speed control) motor they want to sell me? I feel I have eliminated every other possibility except the ecu.
Thanks
Frank

 

[sleeperz]

reply low idle

instead of guessing your problem eastern usa has auto zone/will scan car for free. or pay somebody for a code check, data stream. guessing could cost a bundle. bad coolant temp sensor/vacumn leak. air charge sensor,thermotime switch??????? scan for codes..... east coast i charge 75.00 for code/data stream readout

 

[sideshow]

just pull the isc motor apart

i have cleaned alot of them

they seize up internally
pul lthem apart and u should be able to spin the cetre bit and it should screw in and out

they seize closed usually